What Is Conjugated Linoleic Acid (CLA) and Is It Beneficial?

Conjugated Linoleic Acid, or CLA for short, may sound like a mouthful, but this healthy fat offers some impressive benefits. I’ve covered CLA briefly in my article on grass-fed beef, but today I want to dive a little deeper. I’ve found some evidence-based benefits of CLA and how best to add it into your diet.

What Is Conjugated Linoleic Acid?

CLA is a family of Polyunsaturated Fatty Acids (PUFA). They are primarily produced by bacteria in animals with ruminant stomachs, like cows, goats, and sheep. CLA can also be formed when vegetable oils are bihydrogenated to make margarine (definitely not a source I’d recommend!). Conjugated linoelic acid isn’t just one substance, but a family of about 20 different strains called isomers.

Health Benefits of Conjugated Linoleic Acid

CLA has been around a long time, but there’s been a surge of interest lately in how this substance can benefit our health. Many studies have been done on the isolated supplement added to human or animal diets. There’s also evidence showing the benefits of the whole food form of CLA.

May Reduce Inflammation

Inflammation is the root cause of all sorts of issues in the body. By reducing inflammation, we can address a plethora of health issues and help bring the body back into balance. A study of young male athletes found that 2 weeks of supplementing with CLA improved several inflammatory markers and reduced inflammation.

Improves Brain Inflammation and CNS Function

Astrocytes are special cells that make up a large portion of the brain and are vital to a well functioning brain and body. A neuroscience journal recently published an article that discusses how CLA affects astrocyte cells to tone down inflammation in the central nervous system. CLA may help to regulate the inflammatory response of these special cells to help them function properly, which results in a better performing central nervous system.

Addresses Arthritis Symptoms

Arthritis is another result of inflammation in the body, but this time it’s inflammation of the joints. A study of rheumatoid arthritis sufferers found that supplementing with CLA and vitamin E together produced positive results. Rheumatoid arthritis is an autoimmune disease where the body attacks itself. Researchers saw a decrease in white blood cell counts, meaning the body wasn’t recognizing itself as an invader. It also reduced morning pain and joint stiffness.

Helps with Asthma

Asthma is thought to occur when the body overproduces a substance called leukotrienes, which then cause inflammation and airway constriction. When conjugated linoelic acid is consumed, the body converts it into anti-inflammatory DHA and EPA. The DHA and EPA then work to stop the enzymes that cause the overproduction of leukotrienes to improve asthma symptoms.

Impacts the Immune System

Conjugated linoelic acid is a potent immune system modulator and can increase immune function. A 2005 study in humans found that supplementing with CLA improved participants’ immune function and decreased inflammatory cytokines that impact the immune system. A veterinary journal also found that it protected against immune stimulation across a variety of animal species.

Could Impact Heart Health

There are some claims that conjugated linoelic acid improves heart health, but the results are mixed. Heart disease, cholesterol, and high blood pressure showed improvement in some animal studies, but had the opposite effect in other studies. It’s thought that this may be because different animals metabolize CLA differently. More research is needed to determine how it will influence heart issues in humans.

The researchers also seemed perplexed that milk would contain heart-protecting CLA and heart-damaging saturated fats in the same food. However, that’s operating from the assumption that saturated fats cause heart disease.

In obese children, even when researchers controlled for factors like a special diet and exercise, CLA significantly improved insulin resistance and performed as well as the diabetes drug Metformin. The researchers recommended the children receive 55% of their calories from carbs, which is high for someone with insulin resistance. So even with a high carb diet, which can increase insulin resistance, the CLA was still effective. If these kids had been fed a healthy, whole foods diet, the results may have been even more impressive.

Burns Body Fat

Not only does conjugated linoelic acid have a positive effect on insulin and glucose metabolism, but it helps to improve other factors that contribute to obesity. A long-term, double-blind, placebo-controlled trial of humans (the gold standard in studies) showed that CLA reduced body fat mass significantly. The study also demonstrated that CLA was safe to supplement for an extended period without adverse effects.

Another study of CLA supplementation was done in overweight women. The first two months the women took the supplements results were minimal, but the last two months showed significant improvement. This indicates that CLA is something that needs to be a staple in our diets for a while to see improvement.

Balances Metabolism

Those with chronic obstructive pulmonary disease (COPD) can be prone to undereating because of a lack of appetite. CLA supplementation helped a group of COPD sufferers to increase appetite and macronutrient consumption. CLA also decreased an inflammatory marker that’s associated with high rates of anorexia. This could mean that it helps to regulate the metabolism whether someone is obese or undereating.

Prevents Cancer

Animal studies indicate that even just .05% CLA in the diet can inhibit cancerous tumor growth by over fifty percent! CLA has been shown to help with breast cancer, stomach neoplasia, skin papillomas, and pancreatic cancer cells. Other studies show that CLA can inhibit skin cancer, colorectal, and breast cancer.

A 25-year Finnish study found women who consumed more milk had a much lower chance of breast cancer than those who drank less. CLA was shown to increase tumor-suppressing proteins in both healthy and cancerous breast tissue cells. Only an estimated 5% of cows in Finland are grass-fed, and most are fed imported soy and grains. While I don’t recommend drinking milk from grain-fed cows, the study results show how powerful of a substance CLA can be.

Works as Antimicrobial

A potassium salt of CLA, CLA-K, was tested against bacterial strains like salmonella and strep bacteria. It was able to delay their growth at low concentrations and completely inhibit growth at higher concentrations. It performed better against gram-positive than gram-negative strains. CLA and linoleic acid together demonstrated antibacterial activity against tuberculosis. The combined nutrients inhibited and blocked tuberculosis growth in the body.

While we don’t yet know what exact antimicrobial effect CLA has in the body against a variety of common pathogens, these studies show promise. Since CLA also improves immune function and decreases inflammation, this nutrient can play a big role in keeping sickness at bay.

Strengthens Bones

Conjugated linoelic acid is an important component of the native Chinese Tibetan diet. Researchers found that bone fractures in Tibetans healed significantly better than those in their neighbors, the Hans. When tested in mice, it also improved the quality and strength of healing. In addition to fractures caused by injuries, CLA can also prevent bone loss due to aging. CLA consumption has been shown to help improve and prevent osteoporosis.

Supplementing with CLA

A lot of the studies done on conjugated linoelic acid benefits involved taking a CLA supplement. Since it isn’t just one substance, but a collection of about 20, different supplements contain different parts of the whole. Whenever a substance is isolated from nature we can easily run into problems. Primal guru Mark Sisson points out some of the pitfalls of CLA supplements:

Individual CLA isomers appear to be protective or beneficial in isolated studies…but when you actually feed an animal or human a CLA supplement with the same isomer ratios (not found in nature), the benefits either disappear or get counterbalanced by a negative effect.

There are those who have seen positive results while taking a CLA supplement, although the best source is probably still from real, whole foods.

The Best Sources of Conjugated Linoelic Acid

CLA is highest in grass-fed dairy and beef, though it can also be found in pastured goat’s milk and sheep. Chicken and turkey meat have some CLA, but it’s not nearly as high.

Bacteria in the rumen of animals, like cows, and microorganisms in the digestive system of non-ruminant animals and humans can synthesize CLA from long chain fatty acids. A healthy digestive system is vital for CLA production. In one animal study, rats with a sterile digestive system weren’t able to convert the free linoleic acid into CLA.

Grass-fed Makes for Better Dairy

Just as grass-fed meat is better for you, milk from grass-fed cows is significantly better than dairy from grain-fed.

CLA is about 3-5 times higher in grass-fed cows and is more prolific in animals with healthy digestive systems (that is, eating the foods nature intended!). During the summer, when grass is abundant and lush, these levels peak. CLA levels observed in French summer butter were almost double that of winter butter. Monounsaturated fatty acids (MUFA) was 12% higher, and polyunsaturated fatty acids (PUFA) was 21% higher in the summer butter. Trans vaccenic acid (TVA), the dietary precursor to CLA, was 200% higher in grass-fed summer dairy.

Since the war on fat started in the 1980s, conjugated linoelic acid, naturally occurring omega 3s, vitamin K2, and other healthy fats have dwindled from the conventional diet. Typical store-bought cow milk contains 4.5 mg of CLA per gram of fat, but thanks to the widely held perspective that “fat is bad,” the milk we buy in the store is much lower fat than the milk our grandparents drank. (According to this article in the Washington Post, even whole milk isn’t truly “full fat” but is regulated to contain less than 3.5% fat content, presumably following consumer demand.)

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